Oscillating piston engine for helicopters

ABSTRACT

The system including an internal combustion engine provides the motive power source to the main and tail rotor systems of a helicopter. The engine has a rotating annular cylinder which is rotated in a predetermined ratio to oscillation of a plurality of pairs of oscillating pistons in the cylinder, the pistons being so oscillated so that adjacent pistons are moved alternately apart from one another and toward one another for the respective strokes of the internal combustion engine and having intake port, exhaust ports and ignition means on the rotating annular cylinder located by the rotation of the cylinder between adjacent pistons according to the firing order and cycle of the engine in a typical four stroke cycle system. The engine includes the use of unitary in place of articulated, oscillating crank arms to transmit power from the torque tubes to the crankshaft, and the use of pistons having gabled surfaces that are rigidly connected to the torque discs. The system also includes transmission means means for reducing the torque speed of said crankshaft and for rotating the main rotor head and blades and tail rotor systems of the helicopter.

This application is a continuation-in-part of application U.S. Ser. No.918,374, filed Jul. 23, 1992, now U.S. Pat. No. 5,222,463.

FIELD OF THE INVENTION

This invention relates generally to the field of internal combustionengines. Specifically, this invention relates to certain improvements ina type of internal combustion engine that has a plurality of oscillatingpairs of pistons contained within a rotating annular cylinder to providethe motive power source of rotor systems of a helicopter.

BACKGROUND OF THE INVENTION

The oscillating piston/rotating cylinder engine has been described in P.E. Morgan, U.S. Pat. No. 3,516,392. In this type of engine, an annularcylinder is rotated in a predetermined ratio to the oscillations of aplurality of pairs of oscillating pistons contained within the cylinder.The pistons are oscillated so that adjacent pistons in each pair aremoved alternately toward and away from each other for the respectivestrokes of a four-stroke cycle internal combustion engine. Intake ports,exhaust ports, and ignition means in the rotating cylinder are locatedby the rotation of the cylinder with respect to the pistons inaccordance with the firing order and cycle of the engine. While theMorgan engine is capable of favorable efficiencies as compared withthose of conventional reciprocating piston engines, increasingly rigidstandards of fuel economy and emissions control have made furtherimprovements in mechanical and thermal efficiency highly desirable. Inthis regard, for example, the Morgan engine has a relatively largenumber of moving parts that add weight and complexity, and createfriction losses, while the design of the pistons (essentiallydisc-shaped, with fiat sides) does not optimize the extraction of usefulenergy from combustion during the power stroke.

It would be highly desirable, therefore, to improve the Morgan engine,whereby the advantages of the basic oscillating piston/rotating cylinderdesign are retained, while increasing efficiency by reducing the numberof moving pars and optimizing piston design.

SUMMARY OF THE INVENTION

The improvements herein are primarily the application of an improvedoscillating piston engine to provide the motive power source to drivethe transmission, main rotor blades, and the anti-torque tail rotorsystems of a conventional helicopter.

Present day helicopters are powered by conventional reciprocating pistonaircraft engines or airworthy turbine power engines. The system of thisinvention replaces these engine power systems with the improvedoscillating piston engine as an alternative, fuel efficient motive powerforce for present day helicopters.

As an example, a five inch bore cylinder version of the improvedoscillating piston engine will produce five hundred output shafthorsepower, at a fly away engine system weight of two hundred-thirtypounds. This weight improvement will permit increased payload weight andmore efficient airborne operations utilizing existing helicopter airframe designs.

Broadly, the present invention uses an oscillating piston/rotarycylinder internal combustion engine, of the type described in U.S. Pat.No. 3,516,392 (the disclosure of which is incorporated herein byreference), wherein the improvements include: (a) the use of unitary(rather than articulated), oscillating crank arms, of the "Scotch yoke"type, to transmit power from the torque tubes to the crankshaft; (b) theuse of pistons, having gabled surfaces, that are rigidly connected bymeans of torque discs to torque tubes that transmit power from thepistons to the crankshaft via the crank arms; (c) a magnetic, Halleffect ignition system (instead of a gear-and-shaft driven point/contactdistributor); and (d) a plurality of relatively small balancing discsintegral with the crankshaft, at least one of which is journalled in anannular ball bearing race. These improvements may be more specificallydescribed as follows:

Each of the "Scotch yoke" crank arms comprises an elongated arm memberhaving a circular aperture near one end, through which one of the torquetubes passes. The torque tube is fixed to the arm within the aperture.An elliptical aperture near the other end of the arm receives a ballbearing follower that is concentrically carried on a crank throw of theengine's crankshaft. By this arrangement, the rotational or axialoscillation of the torque tube is first translated into a back-and-forthoscillation of the crankshaft end of the arm, and then translated into arotation of the crankshaft. The Scotch yoke crank arms thus replace thecrank arm, connecting rod, and crank pin of the prior art Morgan enginewith an assembly that provides a more direct connection, with lowerfrictional losses, between the crankshaft and the torque tube, therebymore efficiently transmitting power from the pistons to the crankshaftvia the torque tubes.

Each of the pistons of the engine constructed in accordance with thepresent invention is configured with a pair of oppositely-directed,gabled faces. The pistons in each mutually-oscillating pair of pistonsthus have opposed gabled surfaces facing each other to form asubstantially conical chamber when they approach each other during thecompression stroke. This conical combustion chamber provides increasedcombustion efficiency, while allowing the compression ratio to beselected by appropriately selecting the slope of the piston surface.This combustion chamber configuration also eliminates, or at leastminimizes, the pressure spike associated with combustion in theflat-sided combustion chamber formed by the disc-shaped pistons in theMorgan engine. Moreover, compression damping at the end of combustion isprogressive in the present invention, as opposed to linear in the Morganengine, because of the gabled piston faces.

While the pistons of the Morgan engine are loosely mounted by pins ontoarms extending from a center holder that is fastened to a torque tube,each of the pistons in the present engine is attached to one of a pairof torque discs, each of which, in turn, is welded (or similarly fixed)to one of the torque tubes. As compared with the piston arrangement ofthe Morgan engine, the present arrangement provides better balance,reduced vibration, lower frictional losses, and more efficient transferof power to the torque tubes.

In the Morgan engine, ignition is accomplished by means of aconventional spark ignition system, using a timing mechanism (presumablya distributor) that is operated by a shaft driven by the crankshaftthrough a gear train. Electric current is provided to the spark plugsthrough conductor rings on an exhaust pipe that rotates with thecylinder. The rings make contact with stationary brushes that areconnected to a voltage source (i.e., a generator or alternator) throughthe timing mechanism.

In the present invention, the spark plugs are fired by ignition modulesmounted on the rotating cylinder. The ignition modules contain circuitrythat is triggered to generate a spark inducing voltage in response tomagnetic pulses received, via magnetic pick-ups that rotate with thecylinder, from a plurality of magnets located at appropriate intervalsaround an annular holder mounted on the crankcase. The current thatcreates the spark is delivered to the ignition modules by a brush andslip ring arrangement. This new ignition system provides for moreprecise spark timing, while adjustment of spark advance can be effectedby rotating the magnet holder with respect to the crankcase. Moreover,the gear-and-shaft mechanism for driving the ignition timing mechanismis eliminated, along with its frictional losses, thereby increasingengine efficiency.

The Morgan engine uses a single, relatively massive flywheel at thedistal end of the crankshaft. The present invention replaces this singleflywheel with three smaller flywheels, or balancing discs, located atspaced intervals along the crankshaft, with the center balancing disc(at least) being journalled within an annular ball bearing race toaccept torque arm loads. The result is improved smoothness of operation,better support for the crankshaft, and less crankshaft vibration, ascompared with the Morgan engine.

The above summary provides an overview of the major advantages of thepresent invention over the prior art Morgan engine. These and otheradvantages will be more fully developed in the detailed description thatfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of an improved oscillatingpiston engine, in accordance with a preferred embodiment of the presentinvention;

FIG. 2 is a cross-sectional view of the engine, taken along line 2--2 ofFIG. 1;

FIG. 3 is a cross-sectional view of the engine, taken along line 3--3 ofFIG. 1;

FIG. 4 is a longitudinal cross-sectional view of the engine, similar tothat of FIG. 1, showing the pistons, torque tubes, Scotch yoke arms, andcrankshaft in further detail;

FIG. 5 is an elevational view of the engine, taken along line 5--5 ofFIG. 1;

FIG. 6 is a detailed, partly cross-sectional view of a portion of thecylinder of the engine, showing a pair of mutually oscillatingcylinders, one in cross-section, and one in elevation;

FIGS. 7, 8, and 9 are diagrammatic views illustrating the relativepositions of the pistons, the intake and exhaust ports, and the ignitionmeans during an operational cycle of the engine;

FIG. 10 is a diagrammatic view illustrating of the combination of theimproved oscillating piston engine of the present invention and atransmission driving a helicopter rotor blade using a vertical powertrain; and

FIG. 11 is a diagrammatic view illustrating the combination of theimproved oscillating piston engine and transmission driving a helicopterblade using dual horizontal power trains as shown from above thehelicopter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, FIG. 1 shows an oscillatingpiston/rotating cylinder engine 10, in accordance with a preferredembodiment of the present invention. This disclosure will focusprimarily on the novel aspects of the present invention. For adescription of the general structure and principles of operation of anoscillating piston/rotating cylinder engine, the reader is referred toU.S. Pat. No. 3,516,392, the disclosure of which is incorporated hereinby reference, as previously mentioned.

The engine 10 includes a crankcase 12, in which a rotatable, generallyannular cylinder 14 is mounted. The cylinder 14 contains a plurality ofmutually-oscillating pairs of pistons 16. In the preferred embodiment,there are four such pairs of pistons, at 90° intervals around thecylinder.

In each pair of pistons, one piston is rigidly fixed to it respectiveannular torque disk by means of a mounting stub. As shown in FIG. 1, thefirst piston in the pair is attached by means of mounting stub 17 in acorresponding notch to first annular torque disk 18 that defines theproximal end of a first, or outer, torque tube 20. The other piston inthe pair is attached by means of mounting stub 17 in a notch to a secondannular torque disk 22 that defines the proximal end of a second, orinner, torque tube 24, disposed concentrically within the outer torquetube 20. The pistons are preferably secured to their respective flangesby welding, but attachment means such as roll pins may be used. Thetorque tubes 20 and 24 are generally concentric with the cylinder 14.The cylinder 14 includes a tubular hub 25 that is rotatably supported,in the crankcase 12, between a first tubular sleeve bearing 26,preferably a sleeve made of polytetrafluoroethylene (PTFE), sold underthe registered trademark TEFLON, and a first plurality of rollerbearings 27a. The torque tubes 20 and 24 extend axially through thefirst sleeve bearing 26. A second tubular sleeve bearing 28 (alsopreferably made of PTFE) is disposed between the two torque tubes. Thedistal end of the outer torque tube is rotatably journalled between thesecond sleeve bearing 28 and a second plurality of roller bearings 27b.The inner torque tube 24 is rotatably supported, near its distal end, bya third plurality of roller bearings 27c. The distal end of the innertorque tube 24 is provided with a peripheral flange 29 for axialretention. An anti-friction washer (not shown) may advantageously beprovided between the flange 29 and the crankcase 12.

Thus, the hub 25 and the torque tubes 20 and 24 are concentricallyaligned along a common axis of rotation, and are independently rotatablewith respect to one another, by virtue of the sleeve bearings 26 and 28and the roller bearings 27a, 27b and 27c.

The annular cylinder 14 is formed from a pair ofcircumferentially-divided cylinder segments, an outer segment 30aforming the intake manifold, and an inner segment 30b, that fit togetherto define a generally annular cylinder chamber 31 within the cylinder14. Both cylinder segments 30a and 30b are provided with a plurality ofradial cooling fins 32 at spaced intervals on its exterior surface. Eachof the cylinder segments 30a and 30b has an exterior flange 33, and theflanges 33 are removably secured to each other by suitable means, suchas bolts 34. The cylinder hub 25 extends axially from the inner segment30b.

As shown in FIGS. 2, 5 and 10, the outer cylinder segment 30a isprovided with a pair of diametrically-opposed intake ports 37, each ofwhich communicates with the intake manifold. A pair ofdiametrically-opposed exhaust ports 36 are also provided in the outercylinder segment 30a, offset from the intake ports 37 by about 22.5°.The exhaust from exhaust ports 36 communicates with an exhaust manifold(not shown) before exiting out the bottom of the helicopter.

In the preferred embodiment of the invention, the cylinder 14 (includingthe hub 25), the pistons 16, and the torque tubes 20, 24 are formed of6061-T6-511 aluminum alloy.

Each of the torque tubes 20 and 24 is connected, by means of a so-called"Scotch yoke" mechanism, to a crank throw 38 on a crankshaft 40rotatably journalled in the crankcase 12. As best shown in FIGS. 3 and4, the Scotch yoke mechanism comprises a power arm 41 formed from twomating arm halves 41a and 41b, preferably made from the same aluminumalloy as the torque tubes. Each of the arm halves has a semicircularrecess near its upper end (as oriented in FIG. 3), and a semi-ellipticalrecess near its lower end.

The semicircular recess has upper and lower slots 42, as best shown inFIG. 4. Each torque tube is provided with a groove that registers withthe slots 42. The arm halves are assembled onto the torque tube with thearm slots 42 registering with the torque tube grooves, and a key member46 is inserted between each of the slots and its registering groove toform a "Woodruff" key that firmly secures the arm onto the tube, withthe tube thereby extending through the circular aperture formed by theregistering semicircular recesses of the arm halves. The arm is thusrigidly fastened onto the tube, so that it rotates with the tube withneither axial nor circumferential slippage.

An annular ball bearing race 48 is installed on each of the crank throws38. When the arm halves 41a and 41b of each arm are assembled onto theirrespective torque tubes, the semi-elliptical recesses in the arm halvesform an elliptical aperture 50. During assembly, and before the armhalves are rigidly secured to each other and to the tube, the ballbearing race 48 is captured between the semi-elliptical recesses, sothat it becomes seated in the elliptical aperture 50. The arm halves arethen rigidly fixed to each other and to the tube by means such as bolts52. The ball bearing race 48 is thus free to ride up and down (asoriented in FIG. 3) within the elliptical aperture with the movement ofthe crank throw 38.

It will be appreciated that this Scotch yoke assembly provides a secure,positive mechanical linkage between the torque tubes 20 and 24 and thecrankshaft 40, with fewer moving parts than the articulated, connectingrod linkage of the prior art. Thus, frictional losses are reduced,thereby increasing the efficiency of power transfer. Turning now toFIGS. 1, 4, and 6, the novel piston arrangement of the present inventionis described. Each of the pistons 16 comprises a pair of mating,complementary piston segments 16a, 16b that, when secured to each other,as by roll pins 54, form a somewhat cylindrical piston body withoppositely-directed gabled faces 56. The piston segments are preferablyformed so that, when assembled, they define a hollow interior cavity 58to save weight and to reduce inertial stresses resulting from theoscillation of the pistons.

In actuality, as shown in FIG. 6, the body of each piston is notperfectly cylindrical; it has an axial radius of curvature that allowsit to conform to the radius of curvature of the cylinder chamber 31. Inaddition, the piston body includes several circumferential grooves, intoeach of which is seated a cast iron compression ring 60 having aright-angle cross-section. The piston 16 thus seats against the innerwall 62 and outer wall 64 of the cylinder chamber 31, yet is free tooscillate within the chamber 31. The right-angle compression rings 60are pressure-flexed against the walls of the cylinder chamber 31, sothat their sealing effect is enhanced under compression.

The gabled piston faces 56 are configured so that, during thecompression stroke, a substantially conical combustion chamber 66 isformed between each mutually-oscillating pair of pistons, the apex ofthe combustion chamber 66 being directed inwardly, toward the inner wall62 of the cylinder chamber 31. This configuration of the combustionchamber 66 enhances the creation of an advantageous flame frontprogression throughout the volume of the combustion chamber uponignition of the fuel, thereby providing a more efficient burn forimproved fuel economy and reduced emissions, as compared with theflat-faced pistons of the prior art. Moreover, this configurationeliminates, or at least minimizes, the pressure spike associated withcombustion in the flat-sided combustion chamber formed by flat-facedpistons, thereby substantially reducing inertial stress and vibration.

As shown in FIG. 6, at the end of the compression stroke a gap 67 existsbetween the two pistons, extending from the apex of the combustionchamber 66 to the inner wall 62 of the cylinder chamber 31. This gap 67provides a "squish band" during combustion that produces an advantageousdistribution of combustion pressure, thereby enhancing the engine'sthermal efficiency (the extraction of mechanical energy from thecombustion).

Furthermore, near the end of the power stroke, as each piston ispropelled toward a piston in an adjacent mutually-oscillating pistonpair, the approaching gabled piston faces create a compression dampingthat is progressive along each face, thereby further reducing theinertial stress on each piston at the limit of its travel, as comparedwith flat-sided pistons of the prior art. The crankshaft 40, preferablymachined from a single piece of chrome molybdenum steel, is journalledwithin the crankcase 12 on an axis parallel with the axis of the tubes20 and 24, and with the axis of rotation of cylinder 14. The crankshaft40 is advantageously supported at both ends by suitable bearing means,such as roller bearings 68. A plurality of balancing discs, namely, aproximal balancing disc 70, a central balancing disc 72, and a distalbalancing disc 74, are provided at spaced intervals along the length ofthe crankshaft 40. The balancing discs (preferably at least three, asshown) are advantageously formed as integral parts of the crankshaft 40.The central disc 72 is preferably slightly smaller in diameter than theouter discs 70, 74, and it is journalled within an annular ball bearingrace 76 mounted within the crankcase. The discs 70, 72 and 74 providefor a smoothly continuous rotation of the crankshaft 40, with minimalvibration, and thus replace the single large flywheel of the prior art,while providing better balance for the shaft.

The cylinder 14 is driven by the crankshaft 40 in a 4:1 ratio through agear train comprising a large annular spur gear 78 that meshes with asmall annular spur gear 80. The large gear 78 concentrically surroundsthe tubular cylinder hub 25 and the torque tubes 20, 24, and it issecured to the distal end of the hub 25 by means such as bolts 82. Thesmall gear 80 is secured to the crankshaft 40 between the proximalbalancing disc 70 and the proximal end of the shaft. Thus, thecrankshaft 40 undergoes four revolutions for each revolution of thecylinder 14.

As previously mentioned, the present invention employs fourmutually-oscillating pairs of pistons 16. One piston in each pair isfixed to the first annular flange 18 on the outer torque tube 20, andthe other piston in each pair is fixed to the second flange 22 on theinner torque tube 24. The crank throws 38 on the crankshaft 40 are 180°apart, so that the Scotch yoke arms 41 oscillate their respective torquetubes 20 and 24 generally in opposite directions as the crankshaftrotates, thereby moving the pistons 16 in each mutually-oscillating pairin opposite directions, either toward or away from each other. TheScotch yoke arms 41 are at such an angle with respect to each other asto oscillate the pistons 16 on each tube 20 and 24 in accordance withthe cycle of operation of the engine, as determined by the rotation ofthe cylinder 14, as will be described below. Since the crankshaft 40undergoes four revolutions for each revolution of the cylinder 14, eachmutually-oscillating pair of pistons 16 moves toward and away from eachother eight times during each complete revolution of the cylinder 14.The stroke of movement of each piston 16 in either direction istherefore one-sixteenth of a revolution, or 22.5°. Accordingly, theScotch yoke arms 41 are at a 22.5° included angle about the center ofoscillation when the crank throws are in their extreme positions withrespect to the arms 41, i.e., when the ball bearing races 48 are attheir extremes of travel within the elliptical aperture 50 in the arms41.

The preferred embodiment of the invention employs a spark plug ignitionsystem, as illustrated in FIGS. 1 and 5. The spark ignition systempreferably is a dual spark system, employing first and second pairs ofspark plugs 84 at diametrically opposite positions within the cylinder14. Each pair of spark plugs 84 is fired by a solid state ignitionvoltage generation device 86, mounted between two adjacent cooling fins32 on the exterior of the cylinder 14, and connected to the spark plugs84 by suitable ignition wires 88. The ignition voltage generationdevices 86 are of a type that is triggered to generate an ignitionvoltage pulse in response to magnetic pulse. Such devices arecommercially available from several sources, such as C. H. Electronics,of Riverton, Wyo., and GKD Products, of Garland, Tex. The devices 86 aremodified for use in the present invention only by packaging theircircuitry in a housing that can be installed between the cooling fins32, as shown.

The magnetic means for generating the magnetic pulses comprise eightmagnets 90, and a pair of Hall effect magnetic pickups 92. The magnets90 are equidistantly spaced, at 45° intervals, around an annular magnetholder 94 that is fixed to the crankcase 12 so as to face the magnets 90toward the cylinder 14. The pick-ups 92 are fixed to the inner cylindersegment 30b in diametrically opposite positions, facing the magnets 90,such that the rotation of the cylinder 14 brings the pick-ups 92 intoclose proximity to each of the magnets 90 in turn. Each of the pick-ups92 is electrically connected to one of the ignition voltage generationdevices 86.

Current from an electrical power source, such as a battery (not shown)or an alternator (not shown), is delivered to the ignition voltagegeneration devices 86 through a slip ring 96 mounted on the cylinder hub25 to rotate therewith. Electrical contact between the slip ring 96 andthe positive terminal of the power source is established through aplurality of brushes (not shown). A wire 98 electrically connects theslip ring 96 to each of the ignition voltage generation devices 86. Thenegative terminal of the power source, and the ground leads of the sparkplugs 84, are connected to the crankcase.

As described above, each of the two ignition voltage generation devices86 is triggered to fire its associated pair of spark plugs 84 each timeits associated pick-up 92 passes by a magnet 90 during rotation of thecylinder. Thus, each of the two spark plug pairs fires eight timesduring a complete revolution of the cylinder, yielding a total ofsixteen firings or power strokes for each revolution of the cylinder.The spark plug ignition system described above can be used with suchfuels as gasoline, gasohol, alcohol, or propane, and is the preferredignition system for high-power applications, i.e., over 100 horsepower.

Referring now to FIGS. 7, 8 and 9, the order of firing and oscillationof pistons is illustrated. The pistons 16 connected to the power arm(scotch yoke) 41b on the inner torque tube 24 are marked in thesefigures in sequence, A₁, A₂, A₃, and A₄, and the pistons 16 connected tothe outer torque tube 20 and operated by the power arm (scotch yoke) 41aare in corresponding sequence indicated B₄, B₁, B₂, B₃, B₄.

FIG. 7 corresponds to the position of the crankshaft 40 and the powerarms (scotch yokes) 41a and 41b shown in FIG. 4. In this position, thepairs of pistons A₁ and B₁ and A₃ and B₂ completed the compressionstroke and are in position for firing B₄ the ignition means, spark plugsor by the alternative glow plugs. The other pairs of pistons A₂ and B₂,and A₄ and B₄, just completed their respective exhaust strokes andexpelled the products of combustion from the space between them. Thespaces between A₁ and B₄, and A₃ and B₂, are respectively expanded asthe power strokes are about completed and these spaces are now ready forthe exhaust stroke to begin. The spaces between B₁ and A₂, and B₃ andA₄, have been fully expanded as the intake strokes have been justcompleted and these spaces are ready for their respective compressionstrokes. The annular cylinder (power head) 14 rotates in a clockwisedirection and in the opposite direction to the rotation of thecrankshaft 40. The adjacent exhaust and intake ports 36 and 37 arepaired respectively in diametrically opposite sides of the power head 14and in each pair the intake port 37 and the exhaust port 36 and 221/2°apart to correspond to the 4 to 1 ratio of rotation between the powerhead (anneal cylinder) 14 and the crankshaft 40, and to thecorresponding stroke of oscillation of the pistons 16. As the crankshaft40 rotates 90° from the position shown in FIG. 7, to the position shownin FIG. 8. The power arm 41b is oscillated in a counter-clockwisedirection and the power arm 41a in a clockwise direction. Each power armis oscillated about 111/4° so that they are substantially superimposedone above the other. Correspondingly, the pistons 16, A₁, A₂, A₃ and A₄are moved one half of their strokes in a counter-clockwise directionshown in FIG. 7 and the pistons 16, B₁, B₂, B₃, and B₄ are moved in aclockwise direction as shown in FIG. 7. This corresponds to the powerstroke while pistons 16, A₁ and B₁ are moved apart as well as the powerstroke between pistons 16, A₃ arid B₃ moving apart. At the same time B₁and A₂ are moving together to compress the fuel-air mixture therebetween as well as between B₃ and A₄.

The spaces between the pistons 16, A₂ and B₂ as well as between thepistons 16, A₄ and B₄ moving apart are aligned with the oppositerespective intake ports 37 and continue the intake of the fuel-airmixture. The pistons 16, A₁ and B₄ and the opposite pistons 16, A₃ andB₂ continue to move together for the exhaust stroke between them asaligned with the respective exhaust ports 36 of the annular cylinder orpower head 14.

Further rotation of the crankshaft 40 another 90° from the positionshown in FIG. 8 to the position shown in FIG. 9 another 90° namely atotal of 180° from the position shown in FIG. 7 oscillates the power arm(scotch yoke) 41a in a counter-clockwise direction into the previousposition of power arm (scotch yoke) 41b and oscillates the power arm 41bin a clockwise direction into the initial position of the power arm 41a,shown in FIG. 8, there by completing the expansion of the power strokebetween the pair of pistons 16, A₁ and B₁ and A₃ and B₃ as well ascompleting the exhaust stroke between pistons 16, A₁ and B₄, and A₃ andB₂, and the compression stroke respectively between piston 16, B₁ andA₂, and B₃ and A₄. As compared between FIG. 7 and FIG. 9 during the fullstroke of the pistons 16, in one direction of the 1/4 and are of thecircle of the power head 14, also moves 45° or one eighth of arevolution and thereby advances the spark plug or ignition means to theposition between pistons 16, B₁ and A₂ on one side and B₃ and A₄ on theother side for the next firing.

It is to be noted that the exhaust 36 and the intake 37 ports oropenings are equally spaced angularly from a diameter of the power head14 (annular cylinder) at right angles to the diameter which extendsthrough the opposite ignition means or spark plugs. Therefore, theexhaust port is advanced so as to approach the space between A₁ and B₁for the next consecutive exhaust stroke. The other diametricallyopposite ports are correspondingly shifted.

By continued rotation of the crankshaft 40 over the other half ofrevolution the previously described cycle of operation is repeated insequence between the consecutive pairs of pistons 16.

The power generated by the power stroke is transmitted through thetorque discs 22 and 18 and the respective torque tubes 24 and 20 and tothe power arms (scotch yokes) 41a and 41b to the crankshaft 40 to causethe rotation of the crankshaft 40. In turn, the rotation of thecrankshaft 40 transmitting power through gear 80 and gear 78 in theusual manner rotates the power head (annular cylinder) 14 in a clockwisedirection and by reason of the oscillation of the torque tubes 24 and 20and the strokes of the respective pistons 16 are correspondingly shiftedinto the successive positions for operation in the firing orderheretofore described.

FIG. 10 illustrates a preferred embodiment of the present invention inwhich the improved oscillating piston engine 10 provides the motivepower to drive the main rotor head and blades 100 of the helicopter andthe tail rotor (not shown) for torque control. In addition, it can drivein a vertical power train.

Engine 10 is shown mounted within shroud 107 having an air inlet 108.Engine 10 output shaft 40 rotational speed is reduced through primarytransmission 110. Such transmissions include a clutch equipped SunstrandPlanetary Reduction system manufactured by the Sunstrand Corporation andavailable commercially or the Infinitely Variable Transmission (IVT)developed by Epilogics Inc., Los Gatos, Calif. The latter is thepreferred transmission system.

Infinitely Variable Transmission (IVT) 110 is a beltless, clutchlesstransmission capable of handling the recommended constant high RPMoutput shaft 40 speed produced by piston engine 10. Helicopters operatein a constant main rotor blade rotational speed regime where engine 10and transmission 110 speed are selected by the pilot operator and themain and tail rotor blades pitch angles are varied in a collective andcyclic manner to cause flight in a three axis envelope.

In the case of the single engine 10 vertically configured power train asshown in FIG. 10, an engine rated 500 hp or more is operated at aconstant 4000 rpm cylinder speed, producing 16000 rpm output shaft 40speed which drives IVT 110 to produce the proper speed of rotor headcontrol unit 113 and input shaft 114 to accomplish flight. Thevertically originated power train units are housed within shroud 107 andsuspended fixedly on shock isolation mounts 115. Such mounts aremanufactured and commercially available from Lord Manufacturing, P.O.Box 10039, Erie, Pa. 16514 or Barry Controls, P.O. Box 7710, Burbank,Calif. 91505. Mounts 115 are fixedly attached to the inner wall ofshroud 107 as shown FIG. 10. Shroud 107 is a structural part of thehelicopter and causes air to be conducted from the inlet scoop 108,equipped with an anti-bird screen (not shown), down shroud 107 coolingthe units therein and exiting out outlet 116 at the bottom of thehelicopter, along with the combustion exhaust products from engine 10.Cooling fins 32 on cylinder 14 of engine 10 are angularly canted to actas an air pumping fan during operation to further improved air flowthrough shroud 107. The improved oscillating piston engine 10 isdesigned to operate on various fuels including gasoline, alcohol,gasohol, and propane. In the case of an airworthy vehicle such as ahelicopter, engine 10 operates on aviation grade gasoline with fuelinduction controlled by fuel injection and ignition module 117. Suchmodules are available as those manufactured by the Bob Smith Company,Oceano, Calif.

FIG. 11 illustrates another embodiment of the present invention in whicha horizontally mounted power train is located along each side of themain rotor blade control transmission above a helicopter cabin andreplaces the conventional twin turbine engine power systems.

Two improved oscillating piston engines 10 are located on each side ofmain rotor blade 120 and control transmission 121 as viewed from above.Each engine 10 drives an Infinitely Variable Transmission (IVT) 123through shaft 40 which in turn drives the main rotor blade controltransmission 121 by means of shaft 126 from the torque conversion unit128 to main rotor blade control transmission 121. Each engine 10 powertrain system units are suspended fixedly in shroud 130 on shock isolatedmounts 132. Ram air flows through shroud 130 in the direction shown inFIG. 11. The speed of output shaft 30 and the resulting torque power arecontrolled by the fuel injection and ignition module 116. These dualfuel injection and ignition modules 116 are synchronized and balancedfor equal power output performance. Engine cylinder cooling fins 32 areangle canted to produce air pumping fan action during operation. The airflow through shroud 130 exits through exhaust nozzle 133 along with theengine 10 exhaust products.

What is claimed is:
 1. An internal combustion engine system to providethe motive power source of a rotor system comprising:(a) a rotatingannular cylinder, (b) a plurality of pairs of oscillating pistons insaid cylinder, (c) means to oscillate said pistons so as to alternatelymove adjacent pistons apart from one another and toward one another forthe respective strokes an the internal combustion engine of said system,(d) intake ports, exhaust ports and ignition means on said rotatingannular cylinder for registry with the respective spaces between theadjacent pistons according to the firing order and cycle of said engine,(e) a power take-off shaft in said engine, (f) means to convert theoscillating of said pistons into rotation of said power take-off shaft,(g) transmitting means between said power take-off shaft and saidcylinder to rotate said annular cylinder in a predetermined ratio to theoscillation of said piston for registering said intake ports, exhaustports and ignition means with the respective spaces between saidoscillating pistons in a predetermined sequence, (h) the ratio betweenthe rotation of said shaft and the resulting angular oscillation of saidpistons with respect to the rotating annular cylinder is one oscillationof each piston for each quarter of one revolution of said cylinder, (i)the inner periphery of the cylinder being of circular cross-section andsaid pistons being also of circular cross-section, and piston rings onsaid pistons being in contact with the inner circular periphery of saidcylinder, (j) said means to convert said piston oscillation intorotation including concentric tubes journalled concentrically with saidrotating cylinder, (k) connecting means between the tubes and the powertake-off shaft for converting oscillation of the tubes into rotation ofthe shaft, (l) a crankcase, (m) journal means on said crankcase tosupport said rotating cylinder in a generally horizontal plane, (n) saidoscillation converting means including connecting devices between therespective concentric tubes and said power take-off shaft foroscillating said tubes oppositely to one another during the rotation ofsaid shaft, (o) said inner tube being connected to a fuel vapor intake,(p) an intake manifold on said rotating cylinder connected to the saidintake ports, said inner tube discharging into said intake manifold, (q)piston supporting torque disks being flanges extending from therespective concentric tube to the inner periphery of said rotatingcylinder and to the adjacent pistons so that said pistons are directlyconnected alternately to each of the respective torque disks, (r)transmission means for reducing the torque speed of said power take-offshaft, and for providing the motive force for rotating a rotor system,operably connected to said power take-off shaft, (s) said torque disksbeing slidable relatively to one another according to relative turningmovement of said concentric tubes and extending from the respectivetubes to support said pistons in a balanced position in said cylinder,(t) each of said pistons having a substantially cylindrical sectionwhich is operably seated against the walls of said cylinder and which isattached to each of the respective torque disks, and (u) each of saidconnecting means between each of the concentric tubes and the powertake-off shaft comprises an elongated arm having a circular aperturenear one end thereof and through which one of the respective tubespasses and is fixedly attached thereto and having an elliptical aperturenear the other end thereof operably connected to said power take-offshaft to transmit the axial oscillation of each of said torque discs andthe back-and-forth oscillation into rotation of the power take-offshaft.
 2. The internal combustion engine system defined in claim 1wherein said transmission means comprises:(v) a variable transmission.3. The internal combustion engine system defined in claim 1 wherein saidengine system is housed within:(w) a cooling and exhaust shroud havingan inlet and an outlet.
 4. The internal combustion engine system definedin claim 1 wherein:(x) each of said pistons being made of twocomplemental substantially cylindrical sections having a pair ofoppositely-directed gabled faces, (y) said gabled faces being configuredto form a substantially conical combustion chamber at the end of thecompression stroke, and (z) means to align and secure said substantiallycylindrical sections together.
 5. The internal combustion engine systemdefined in claim 3 wherein:(aa) cooling fins are operably mounted ontosaid rotating annular cylinder to provide fan pumping action to draw airinto the rotor system and down through the inlet of said shroud to coolsaid engine and to exhaust combusted fuel gases from said exhaust portto the outlet of said shroud.
 6. An internal combustion engine system toprovide the motive power source of main and tail rotor systemscomprising:(a) a crankcase, (b) an annular cylinder, (c) a hub of saidannular cylinder rotatably journalled on said crankcase, (d) an innertube and an outer tube concentrically journalled in said crankcase andin said hub, (e) a plurality of circumferentially equally spaced pistonsseated within said annular cylinder, (f) a crankshaft journalled in saidcrankcase, (g) connecting means between said crankshaft and said tubesfor oscillating said tubes angularly about the axis of said cylinder andoppositely to one another for the respective strokes of said pistons bythe rotation of the crankshaft and to transmit power from said tubes tosaid crankshaft, (h) circumferentially spaced intake ports, outlet portsand ignition means on said cylinder, (i) means to transmit rotation fromsaid crankshaft to said cylinder so as to register said ports and saidignition means with the respective spaces between said pistons in apredetermined sequence relative to the respective strokes of saidpistons, (j) the axis of rotation of said cylinder and of saidcrankshaft being parallel, (k) an intake manifold on said cylinderconnected to said intake ports, (l) said inner tube extending to saidintake manifold at one end thereof and through said crankcase at itsother end and being connectable at said other end to a combustible fuelsupply, (m) a plurality of torque discs connecting the hub to thecylinder, (n) variable transmission means for reducing the torque speedof said crankshaft and for providing force for rotating main rotor headand blades and tail rotor systems, operably connected to saidcrankshaft, (o) said connecting means comprises an elongated yoke armhaving a circular aperture near one end thereof and through which one ofthe respective tubes passes and is fixedly attached thereto and havingan elliptical aperture near the other end thereof operably connected tosaid crankshaft to transmit the axial oscillation of each of said torquediscs and the back-and-forth oscillation into rotation of thecrankshaft.
 7. The internal combustion engine system defined in claim 6wherein:(p) each of said pistons being made of two complementalsubstantially cylindrical sections having a pair of oppositely-directedgabled faces, said substantially cylindrical sections which are operablyseated against the walls of said cylinder and one section of which isfixedly attached to each of the respective torque discs, said pistonsbeing circumferentially spaced from one another, said gabled faces beingconfigured to form a substantially conical combustion chamber at the endof the compression stroke.
 8. The internal combustion engine systemdefined in claim 6 wherein said engine is housed within:(q) a coolingand exhaust shroud having an inlet and outlet.
 9. The internalcombustion engine system defined in claim 8 wherein:(r) cooling fins areoperably mounted onto said annular cylinder to provide fan pumpingaction to draw air into the main rotor system and down through the inletof said shroud to cool said engine and to exhaust combusted fuel gasesfrom said exhaust port to the outlet of said shroud.
 10. The internalcombustion engine system defined in claim 6 wherein:(s) the adjacentsurfaces of said torque discs are in sliding contact therebetween, saidsurfaces having annular grooves therein, and (t) annular packingelements positioned in said grooves.
 11. The internal combustion enginesystem defined in claim 6 wherein:(u) said ignition means comprises aplurality of spark plugs, voltage generation means, and ignition wiresconnected between said spark plugs and said ignition wires.
 12. Theinternal combustion engine system defined in claim 11 wherein:(v) saidvoltage generation means comprises magnetic means to generate magneticpulses for generating ignition voltage.
 13. The internal combustionengine system defined in claim 6 wherein four pairs of said pistons areprovided in diametrically opposite symmetrical arrangement, and whereinthe ratio of rotation of the cylinder to the oscillation of the pistonsis one revolution of the cylinder for eight strokes of oscillation ofeach piston.
 14. The internal combustion engine system defined in claim6 wherein:(w) said cylinder is formed of a pair of super-imposedcomplemental rings of semi-cylindrical cross-section, (x) a hub sectionon each ring forming said hub means, and (y) said torque discs and saidtubes being spaced so as to accommodate said oscillating pistontherebetween.
 15. The internal combustion engine system as defined inclaim 14 wherein:(z) each stroke of oscillation of each pistoncoinciding to about one-sixteenth of a revolution of cylinder, (aa) aninlet port and an exhaust port located in a pair spacedcircumferentially on the cylinder about twenty-two and a half degreesapart, and diametrically opposite to one another paired inlet ports andexhaust ports, and (bb) said ignition means being at diametricallyopposite areas of said cylinder and circumferentially at about rightangles from the respective pairs of inlet and exhaust ports.
 16. Theinternal combustion engine system as defined in claim 6 wherein:(cc)polytetrafluoroethylene is positioned between said inner tube and saidouter tube.
 17. The internal combustion engine system as defined inclaim 6 wherein:(dd) a plurality of balance wheels are positioned onsaid crankshaft.
 18. An internal combustion engine system housed withina shroud to provide the motive power source of a rotor systemcomprising:(a) a rotating annular cylinder, (b) a plurality of pairs ofoscillating pistons in said cylinder, (c) means to oscillate saidpistons so as to alternately move adjacent pistons apart from oneanother and toward one another for the respective strokes of an internalcombustion engine of said system, (d) intake ports, exhaust ports andignition means on said rotating annular cylinder for registry with therespective spaces between the adjacent pistons according to the firingorder and cycle of said engine, (e) a power take-off shaft in saidengine, (f) means to convert the oscillating of said pistons intorotation of said power take-off shaft, (g) transmitting means betweensaid power take-off shaft and said cylinder to rotate said annularcylinder in a predetermined ratio to the oscillation of said piston forregistering said intake ports, exhaust ports and ignition means with therespective spaces between said oscillating pistons in a predeterminedsequence, (h) a crankcase, (i) journal means on said crankcase tosupport said rotating cylinder in a generally horizontal plane, (j) anintake manifold on said rotating cylinder connected to the said intakeports and a fuel vapor intake, (k) transmission means for reducing thetorque speed of said power take-off shaft and for providing the motiveforce, and for rotating a rotor system, operably connected to said powertake-off shaft, (l) a cooling and exhaust shroud having an inlet and anoutlet in which said engine system is housed, and (m) cooling finsoperably mounted onto said rotating annular cylinder to provide fanpumping action to draw air into the inlet of said cooling and exhaustshroud and down through said shroud to cool said engine and to exhaustcombusted fuel gases from said exhaust port to the outlet of saidshroud.
 19. The internal combustion engine system defined in claim 18wherein said transmission system comprises:(n) a variable transmission.20. The internal combustion engine system defined in claim 18wherein:(o) one of said internal combustion engine systems is located oneach side of the rotor system, and (p) transmission means are operablyconnected to said power take-off shaft of each of said engines.